
SUSAN corner detector. More...
Functions  
AFAPI features  susan (const array &in, const unsigned radius=3, const float diff_thr=32.0f, const float geom_thr=10.0f, const float feature_ratio=0.05f, const unsigned edge=3) 
C++ Interface for SUSAN corner detector. More...  
AFAPI af_err  af_susan (af_features *out, const af_array in, const unsigned radius, const float diff_thr, const float geom_thr, const float feature_ratio, const unsigned edge) 
C Interface for SUSAN corner detector. More...  
SUSAN corner detector.
SUSAN is an acronym standing for Smallest Univalue Segment Assimilating Nucleus. This method places a circular disc over the pixel to be tested (a.k.a nucleus) to compute the corner measure of that corresponding pixel. The region covered by the circular disc is M, and a pixel in this region is represented by \(\vec{m} \in M\) where \(\vec{m}_0\) is the nucleus. Every pixel in the region is compared to the nucleus using the following comparison function:
\( c(\vec{m}) = e^{{(({I(\vec{m})  I(\vec{m}_0))} / t})^6}\)
where t is radius of the region, I is the brightness of the pixel.
Response of SUSAN operator is given by the following equation:
\( R(M) = \begin{cases} g  n(M) \quad \text{if } n(M) < g\\ 0 \quad \text{otherwise},\\ \end{cases}\)
where \( n(M) = \sum\nolimits_{\vec{m} \in M} c(\vec{m})\), g is named the geometric threshold and n is the number of pixels in the mask which are within t of the nucleus.
Importance of the parameters, t and g is explained below:
AFAPI af_err af_susan  (  af_features *  out, 
const af_array  in,  
const unsigned  radius,  
const float  diff_thr,  
const float  geom_thr,  
const float  feature_ratio,  
const unsigned  edge  
) 
C Interface for SUSAN corner detector.
[out]  out  is af_features struct composed of arrays for x and y coordinates, score, orientation and size of selected features 
[in]  in  is input grayscale/intensity image 
[in]  radius  nucleus radius for each pixel neighborhood 
[in]  diff_thr  intensity difference threshold a.k.a t from equations in description 
[in]  geom_thr  geometric threshold 
[in]  feature_ratio  is maximum number of features that will be returned by the function 
[in]  edge  indicates how many pixels width area should be skipped for corner detection 
in
is a 3d array, a batch operation will be performed. AFAPI features af::susan  (  const array &  in, 
const unsigned  radius = 3 , 

const float  diff_thr = 32.0f , 

const float  geom_thr = 10.0f , 

const float  feature_ratio = 0.05f , 

const unsigned  edge = 3 

) 
C++ Interface for SUSAN corner detector.
[in]  in  is input grayscale/intensity image 
[in]  radius  nucleus radius for each pixel neighborhood 
[in]  diff_thr  intensity difference threshold 
[in]  geom_thr  geometric threshold a.k.a t from equations in description 
[in]  feature_ratio  is maximum number of features that will be returned by the function 
[in]  edge  indicates how many pixels width area should be skipped for corner detection 
in
is a 3d array, a batch operation will be performed.